|Publication number||US7329878 B2|
|Application number||US 10/565,373|
|Publication date||Feb 12, 2008|
|Filing date||Jul 24, 2004|
|Priority date||Jul 25, 2003|
|Also published as||CN1830053A, CN1830053B, EP1649483A1, EP1649483A4, US20060255286, WO2005010918A1|
|Publication number||10565373, 565373, PCT/2004/1841, PCT/KR/2004/001841, PCT/KR/2004/01841, PCT/KR/4/001841, PCT/KR/4/01841, PCT/KR2004/001841, PCT/KR2004/01841, PCT/KR2004001841, PCT/KR200401841, PCT/KR4/001841, PCT/KR4/01841, PCT/KR4001841, PCT/KR401841, US 7329878 B2, US 7329878B2, US-B2-7329878, US7329878 B2, US7329878B2|
|Inventors||Ho Seob Kim|
|Original Assignee||Cebt Co., Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Referenced by (6), Classifications (22), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates, in general, to methods for manufacturing lens assemblies for electron beam microcolumns and lens assemblies manufactured by the methods and, more particularly, to a method for manufacturing a lens assembly for an electron beam microcolumn and the lens assembly which has a high resolution and is elaborate and is used in electron beam lithography and in electron microscopes.
Electron emission sources operating under basic principles of scanning tunneling microscopes (STM) and electron beam microcolumns based on electron optical elements having microstructures were introduced in 1980. In electron beam microcolumns, microelements are elaborately assembled to minimize optical numerical values, thus forming improved electron columns. Furthermore, due to the microstructures, arrangements of a plurality of electron beam microcolumns are used in serial or parallel multi-electron columns.
The microcolumns are high-aspect-ratio micromechanical structures including microlenses and deflectors. Microlens assemblies constituting the microcolumns are multi-layered silicon chips (with membranes windows for lens electrodes), or silicon membranes which are spaced apart from each other by insulating layers each having a thickness of 100 to 150 μm. The microlens assemblies of the microcolumns include bores having diameters of a few to several hundred micrometers. For optimum performance, the roundness of the bores must be in the nanometer range and the alignment error between elements is required to be within a range of less than 1 μm.
To assemble the lens assembly of the conventional microcolumn, the microlenses, made of silicon, and the insulating Pyrex spacers are sequentially layered one after another. Thereafter, the layered lenses and insulating materials are anodic-bonded together. The anodic-bonding is an electrochemical process of coupling glass to metal and semiconductors, as shown in
This process was previously used for single sided bonding only. However, recently, this process has been extended to multilayer bonding. After the first silicon-to-glass bond, another silicon chip or membrane may be bonded to the free surface of the glass by reversing the applied voltage, as shown in
However, the above-mentioned anodic bonding is executed after a plurality of microlenses and insulating layers are alternately layered. Therefore, while a layered product of the lens assembly of the microcolumn, which requires high accuracy in alignment, is heated to a high temperature and cooled, the layers may become misaligned, and thereby, the accuracy may be deteriorated. Furthermore, for the anodic bonding, an upper electrode is connected into a contact point type using a wire. Accordingly, an excessively long time is required to anodic-bond the lens assembly through the whole area using wire voltage.
In addition to the above-mentioned assembling method, a lens assembly of a microcolumn using laser spot bonding was proposed in Korean Patent Application No. 2001-7003679 (Filed: 22 Mar. 2001), which will be described herein with reference to
In the lens assembly 93, the first insulating layer 77 and the second insulating layer 87 each have two extension parts which horizontally protrude outwards from opposite edges of each of the first insulating layer 77 and the second insulating layer 87. That is, the first insulating layer 77 and the second insulating layer 87 have ear parts 79 and 88, respectively. Because a microlens aperture of the microcolumn has a diameter of 2 μm or less, it is imperative that multiple layers of the microcolumn be precisely aligned.
When a laser beam is emitted from a laser, the laser beam substantially passes through the first insulating layer 77 to heat a surface of the second microlens 85. Thus, the first insulating layer and the surface of the microlens are instantaneously welded together. In the same manner, due to the laser beam passing through parts 84 to be welded, a surface of the second insulating layer 87 is instantaneously welded.
In other words, while silicon of the microlenses is melted at a high temperature and, thereafter, recrystallized, an adjacent portion of the insulating layer is heated. At approximately 400 to 500° C., the glass insulating layer begins to flow. At this time, a micro-weld of approximately 100 μm-500 μm in diameter is formed between two layers at the location of a laser spot weld or micro-weld 84.
However, in the case of the lens assembly of the microcolumn spot-bonded by the laser through the above-mentioned method, the lens assembly is maintained only by the welding parts 84 welded by the laser. Therefore, the lens assembly is problematic in that difficulty in maintenance of the arrangement exists, thus reducing stability. Furthermore, the lens assembly is problematic in that each insulating layer must have the ear part 79, 88 to provide a separate portion for laser welding.
In addition, it is disadvantageous in that an action of layering the lenses using the designated portions (ear parts) must be sequentially executed from the bottom.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for manufacturing a lens assembly of a microcolumn and the lens assembly, in which a microlens assembly set is formed by anodic-bonding a microlens and an insulating layer together in a preliminary process, so that bonding between two layers is stable, thus reducing assembling time.
Another object of the present invention is to provide a method for manufacturing a lens assembly of a microcolumn and the lens assembly, in which the lens assembly of the microcolumn is formed by layering a plurality of microlens assembly sets, while spot bonding is executed by a laser to easily assemble the microlens assembly sets and, thereafter, anodic bonding is executed to provide the firm bonding, thus enhancing the stability of the lens assembly.
A further object of the present invention is to provide a method for manufacturing a lens assembly of a microcolumn and the lens assembly, which ensures a wire path connected to each microlens and a stable wire connection, and is regardless of the order of layering microlenses, thus increasing the productivity of the lens assembly process.
The present invention provides a lens assembly of a microcolumn, in which a plurality of microlens assembly sets is first prepared and, thereafter, the microlens assembly sets are simply layered on top of another, thus reducing the time required for layering the microlens assembly sets.
In the present invention, a microlens and an insulating layer constituting each microlens assembly set are bonded together while the microlens is rotated on the insulating layer at a predetermined angle. Furthermore, the microlens assembly sets also are layered on top of one another while being rotated on each other at predetermined angles. Thus, laser spot bonding for maintenance of the arrangement can be easily executed. In addition, a laser beam can be simply scanned in a desired direction.
Moreover, because anodic bonding is executed using a flat plate electrode, the arrangement of the bonded layers is stably maintained and, as well, the time for the anodic bonding is reduced.
Although the preferred embodiments of the present invention will be explained for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
In an aspect, the present invention provides a method for manufacturing a lens assembly of an electron beam microcolumn having a plurality of microlenses each provided with a hole at a central position thereof, and a plurality of insulating layers alternately interposed between the microlenses. The method includes: forming at least one first microlens assembly set by anodic-bonding an insulating layer and a microlens together so that a part of a surface of the insulating layer is not covered by the microlens; layering the first microlens assembly set on a second microlens or a second microlens assembly set while aligning the holes of the microlenses, so that the second microlens or the microlens of the second microlens assembly set is in contact with the insulating layer of the first microlens assembly set, while the part of the insulating layer of the first microlens assembly set, not covered with the first microlens, is in contact with the second microlens or the microlens of the second microlens assembly set; and scanning a laser beam to bond the part of the insulating layer of the first microlens assembly set, not covered with the first microlens, to the second microlens or the microlens of the second microlens assembly set by passing the laser beam through the part of the insulating layer of the first microlens assembly set, thus welding the first microlens assembly set to the second microlens or the microlens of the second microlens assembly set.
In another aspect, the lens assembly of the present invention manufactured through the above-mentioned method, includes a first microlens assembly set formed by anodic-bonding a microlens and an insulating layer together, so that a plurality of microlens assembly sets is laser-spot-bonded together by the scanning of a laser beam in a predetermined direction while a welding spot is formed between the insulating layer of the first microlens assembly set and a microlens of a second microlens assembly set.
[Mode for Invention]
Hereinafter, a method for manufacturing a lens assembly of an electron beam microcolumn will be described.
First, the method for manufacturing the lens assembly of the electron beam microcolumn according to the present invention is as follows in brief. A microlens assembly set is formed by anodic-bonding a microlens and an insulating layer together using a flat plate electrode. Such microlens assembly sets are layered on top of another. Spot bonding using a laser is executed to bond the layered microlens assembly sets together. Thereafter, anodic bonding is executed to more stably bond the layered microlens assembly sets bonded together by the spot bonding.
As shown in
The anodic bonding of the first microlens assembly set set_1 will be explained in detail. As shown in
At this time, the microlens and the insulating layer are arranged while aligning circular holes 108 which are provided at central positions on the microlens and the insulating layer. The holes 108 are used as a path for scanning an electron beam in the lens assembly of the completed microcolumn. Typically, the arrangement of the holes of the lens assembly of the microcolumn means the alignment of the holes of microlenses. The holes of the insulating layers are larger than the holes of the microlenses. Therefore, the hole arrangement of the microlens assembly set is formed in a short time, unlike the hole arrangement of the microlenses. That is, the holes of the microlens and the holes of the insulating layers can be aligned with the naked eye. After the arrangement of the holes, the anodic bonding is directly executed. As such, the formation of the microlens assembly set is attained in a short time.
The description of the rotating angle is as follows. Each layer is rotated on a neighboring layer around each hole 108 at a predetermined angle to expose a predetermined portion to the outside, thus forming a passage of a laser beam during a laser spot bonding which will be described later herein. In the case of a rotating angle of 45°, as shown in
In the case of a small rotating angle, as shown in
As such, after the microlens assembly sets are prepared, a desired number of microlens assembly sets are layered on top of one another to manufacture a lens assembly of a microcolumn which has a predetermined thickness. According to the embodiment of the present invention, referring to
When laser beams are scanned in a direction of the arrow of
Furthermore, layering of the embodiment of
As shown in
A method of layering circular microlenses and circular insulating layers on top of one another is shown in
In the meantime, after the lens assembly is completed by laser-spot-bonding the first, second and third microlens assembly sets set_1, set_2 and set_3, the whole microlens assembly sets set_1, set_2 and set_3 may be anodic-bonded using electrodes placed on upper and lower surfaces of the lens assembly, thus enhancing bonding force.
Furthermore, in the lens assembly, to apply a desired bonding force to the microlens assembly sets through laser spot bonding, it is necessary to layer the microlens assembly sets such that a microlens is placed at each of the uppermost and lowermost layers. To achieve the above-mentioned purpose, a microlens is placed at the lowermost layer in place of the microlens assembly set. If the uppermost layer is an insulating layer, a microlens is placed at the uppermost layer in place of the microlens assembly set. In other words, in the embodiment of
Additionally, the insulating layers and the microlenses are layered on top of one another while being rotated on each other in the same direction and at the same angle, such that the microlenses are placed at the uppermost and lowermost layers. Thereafter, the layered lens assembly is anodic-bonded. Alternatively, a separately manufactured microlens assembly set, in which an insulating layer is interposed between two microlenses, may be used to form the lens assembly of the microcolumn. That is, a microlens assembly set is not limited to being formed by bonding one microlens and one insulating layer together in a preliminary step. Unimportant portions in the hole arrangement may be arranged in advance to form the microlens assembly set by a single anodic bonding process. However, in the case that the hole arrangement is important, it is preferable that the insulating layer and the microlens are preliminarily anodic-bonded.
In the preferred embodiments of the present invention, both the microlens 102, 104, 106, 302, 202, 204 and the insulating layer 101, 103, 105, 301, 201, 203 have holes 108. Each hole 108 has a circular shape for ease of maintenance of the arrangement of the lens assembly. In detail, although each layer is rotated on a neighboring layer, because the holes 108 have a circular shape, the arrangement of the layers is stably maintained. As such, each hole 108 has a circular shape to prevent a rotating axis of the layers from undesirably shaking while the layers are rotated. The above-mentioned hole is provided according to the preferred embodiment of the present invention. However, the hole is not limited to a circular shape, but may have a polygonal shape, such as a triangular or rectangular shape. In the case of an equilateral polygonal hole, a microlens is layered on an insulating layer such that a polygonal hole of the microlens and a polygonal hole of the insulating layer correspond in shape to each other. Of course, microlens assembly sets are layered on top of one another so that polygonal holes of the microlens assembly sets correspond in shape to each other. In other words, the microlens assembly sets are arranged such that those polygonal holes correspond in shape to each other from the uppermost microlens to the lowermost rotated microlens. Thus, a laser beam can pass through the polygonal holes of the layered microlens assembly sets in the same manner as through those of the microlens assembly sets having the circular holes.
With reference to an embodiment of
Furthermore, in the case that a hole also has a triangular or polygonal shape, a predetermined angle, at which microlens assembly sets are rotated on each other, is previously determined. According to the determined angle, holes with a predetermined phase angle difference are formed on microlenses of the microlens assembly sets. Then, the microlens assembly sets can be layered on top of another in the same manner as that of the above-mentioned layering method. However, preferably, the holes have the phase angle difference equal to that of the embodiment of
Moreover, in the embodiment of
In the embodiments of the present invention, although the bond of three or less microlens assembly sets set_1, set_2 and set_3 has been explained, more microlens assembly sets may be layered and bonded together in the same manner.
In the method for manufacturing the microlens and the lens assembly according to the present invention, a conventional wire path connected to each lens may be formed on the portions of each microlens, on which the laser spot bonding is executed. Thus, a stable wire connection is ensured. In other words, the wiring is accomplished using a conventional deposited gold pad on the microlens' portions for the laser spot bonding. Therefore, the wiring connection is physically and electrically stable. The wire path also is easily ensured.
A lens assembly according to the present invention is utilized for a microcolumn which is used in an electron beam lithography and in an electron microscope.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US5122663 *||Jul 24, 1991||Jun 16, 1992||International Business Machine Corporation||Compact, integrated electron beam imaging system|
|US6195214 *||Jul 30, 1999||Feb 27, 2001||Etec Systems, Inc.||Microcolumn assembly using laser spot welding|
|US6281508 *||Feb 8, 1999||Aug 28, 2001||Etec Systems, Inc.||Precision alignment and assembly of microlenses and microcolumns|
|US6324010 *||Feb 29, 2000||Nov 27, 2001||Eastman Kodak Company||Optical assembly and a method for manufacturing lens systems|
|US6369385 *||May 5, 1999||Apr 9, 2002||Applied Materials, Inc.||Integrated microcolumn and scanning probe microscope arrays|
|US20020125440 *||Mar 7, 2001||Sep 12, 2002||Applied Materials, Inc.||Method for fabrication of silicon octopole deflectors and electron column employing same|
|US20050199821 *||Mar 12, 2004||Sep 15, 2005||Zyvex Corporation||Compact microcolumn for automated assembly|
|US20050199822 *||Nov 12, 2004||Sep 15, 2005||Zyvex Corporation||Mems based charged particle deflector design|
|US20060255286 *||Jul 24, 2004||Nov 16, 2006||Kim Ho S||Method for manufacturing a lens assembly of microcolumn and lens assembly of microcolumn manufactured by the same|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8044351 *||May 29, 2006||Oct 25, 2011||Cebt Co. Ltd||Micro-column with simple structure|
|US8071944 *||Sep 1, 2005||Dec 6, 2011||Cebt Co. Ltd.||Portable electron microscope using micro-column|
|US8829465 *||May 10, 2012||Sep 9, 2014||Canon Kabushiki Kaisha||Charged particle beam lens having a particular support electrically insulating first and second electrodes from each other|
|US8835848 *||Feb 13, 2014||Sep 16, 2014||Industry-University Cooperation Foundation Sunmoon University||Ultra-miniaturized electron optical microcolumn|
|US20080203881 *||May 29, 2006||Aug 28, 2008||Ho Seob Kim||Micro-Column With Simple Structure|
|US20080315096 *||Sep 1, 2005||Dec 25, 2008||Ho Seob Kim||Portable Electron Microscope Using Micro-Column|
|U.S. Classification||250/396.00R, 313/251, 250/310, 373/80, 250/492.3, 219/603, 250/311|
|International Classification||H01J9/18, H01J37/28, G02B7/02, H01J37/26, G21K7/00, G01N23/00, H01J37/12|
|Cooperative Classification||H01J2237/31774, H01J37/28, H01J9/18, H01J2237/1205, H01J37/12|
|European Classification||H01J37/28, H01J9/18, H01J37/12|
|Jan 20, 2006||AS||Assignment|
Owner name: CEBT CO., LTD., KOREA, REPUBLIC OF
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KIM, HO SEOB;REEL/FRAME:017489/0080
Effective date: 20060116
|Aug 11, 2011||FPAY||Fee payment|
Year of fee payment: 4
|Jun 3, 2015||FPAY||Fee payment|
Year of fee payment: 8